Sudan’s former President Omar al-Bashir has been moved to Kobar maximum security prison, days after he was deposed in a military coup.
Reports say the ex-leader has until now been detained at the presidential residence under heavy guard.
He is reportedly being held in solitary confinement and is surrounded by tight security.
Months of protests in Sudan led to the ousting and arrest of the long-time ruler on Thursday.
Uganda’s Minister for Foreign Affairs Henry Oryem Okello told Reuters news agency the country would consider offering the deposed leader asylum if he applied, despite an arrest warrant issued by the International Criminal Court (ICC).
As an ICC member, Uganda would have to hand over Mr Bashir if he arrived in the country. The ICC has not yet commented.
Until now, Mr Bashir’s whereabouts since his removal were unknown. The coup leader at the time, Awad Ibn Auf, said Mr Bashir was being detained in a “safe place”. He himself stood down soon afterwards.
Lt Gen Abdel Fattah Abdelrahman Burhan was then named as head of the transitional military council, to become Sudan’s third leader in as many days.
Demonstrators have vowed to stay on the streets until there is an immediate move to civilian rule.
Mr Bashir led Sudan for close to 30 years.
He is accused of organising war crimes and crimes against humanity in Sudan’s western Darfur region, for which the ICC issued an arrest warrant.
After months of protests – starting in response to a rise in living costs and morphing into calls for the government to resign – Sudan’s military toppled Mr Bashir in a coup on Thursday.
The transitional military council was set up in the wake of his removal, and has said it will stay in place for a maximum of two years until a civilian government can be put in place.
During his three-decade rule, Omar al-Bashir sent many of his political opponents to Kobar prison. Now his relatives say that’s where he’s been taken.
The conditions there are shockingly different from the splendour of the presidential residence, where he had been under house arrest since Thursday.
Many Sudanese people hope that their former president will be punished for the atrocities committed on his watch. The generals now running the country say Mr Bashir will not be transferred to the ICC but will be tried in Sudan.
If they see concrete evidence that he is in prison, protestors calling for a return to civilian rule may feel at least partly reassured that the country can move on from its oppressive past.
Demonstrators remain camped out the military headquarters in the Sudanese capital, Khartoum.
Reports on Monday said there had been efforts to disperse a sit-in, but protesters joined hands and troops stepped back from a confrontation.
The Sudanese Professionals’ Association (SPA), which has spearheaded the protests, urged supporters to stop efforts to disperse them, calling on demonstrators to “protect your revolution and your accomplishments”.
An SPA spokesman told the BBC that the group “completely rejected” the transitional military council leading the country, and said protesters seek the dismantling of state intelligence agencies and the “full dissolution of the deep state”.
Military council spokesman Maj Gen Shams Ad-din Shanto announced a raft of new measures on Sunday, including the end of censorship and new heads of the security forces.
The council has arrested former government members, he said, and will put in place whatever civilian government and whichever prime minister opposition groups agree.
But while the council promised not to remove protesters from their sit-in, the major also called on them to stop unauthorised roadblocks and “let normal life resume”.
“Taking up arms will not be tolerated,” he added.